Preparation of 2-alkyl-1-alkenes



Patented Mar. 2, 1954 2;6'71,121: PREPARATION .OF 2'-ALKYL-1-ALKENES Fred W Banes; Westfield; and- William- E Fitz Gerald, Elizabeth; N. J., assignors to Standard Oil;DeveIopment::.Company;-' a; corporation; of:

Delaware No Drawing; Application December 23,1949;

Serial. N o.

This invention relates 1 to: the preparation L of 2=alkyl-'-.1 a-lkenes: containing- 7 to 36. carbon atoms per molecule; More particularly" the in vention= is concerned with Y a novel process for the preparation of- 2-alkyl-1-alkenes :by reacting amono-alkyl methyl carbinol with ethylene-in the presence 7 of a peroxide activator under: required temperature and 1 pressure conditions to form zalkyl z-alkanols and subsequently dehydratingthe 2 alkyl-2 alkanols to 2'alkyl-'--l'- allrenes.

2!alkyl'-1'-alliene.s-;- are alpha tertiary monoolefins-ofthetype:

Journal. .Am;; Chem; 800., volume 54,. page-751, 1932;. 2.- alkyl-2alkanols:; are: alcohols; of the type:

c OHCH:

It isan. object: of. this. invention. therefore Ito.

prepare alpha;tertiary'monorolefins ofsthe type:

\QECH: Rf

wheresR' is a straight chainalkyl'radicalot 440 carbon: atoms and R1 isan" al-kyl *radical oil-4" carbon atoms. Olefins of this type are highly desirable because, being of the terminal type,

they are highly reactiveand'enter into "such well known reactions alkylation; etc.

as polymerization, oxonation, Many of i the" higher- 2=alkyl-*1-' alkenes prepared. accordingtothe processof this- Type 'III olefins containing1a=total of7 150.36 carbon atoms, preferably '7 to; 2.7 'carbon' atoms; are" particularly inventionrare new compounds:

desirable as raw. materialsior. chemical synthesis, synthetic lube oils; detergentalkylates, oil-soluble sulfonates, etc.

There is described in Serial No. 130;784"filed December 2, 1949, of which this applicationis a continuation-in-part, a process whereby alcohols suchas: methanol, ethanol, isopropanol, the butanols, the pentanols, .etc.;.and;.also.cycloalie" phatic alcohols are reacted with such olefins as atoms, andslRt is.-the:hydro.carbon :side cha-in: of

the original secondary alc0h0L- Thus in-the case of theaproduct madecfrom isopropanol IRI- .would be CH3; from secondary butanol R1=wouldabe C2Hs,..etcl

It has now been found that 2-alkyl-1-alkenes of the type described may be prepared by reacting a mono-alkyl methyl carbinol with ethylene accordingto theprocess'describedi rSerial No. 130,784 filed December 2, 1949, to produce 2-alk'yl=2+alkanols of thetype-z' Conan R1 andv subsequently dehydratinglythez.lattera alcohol of increased molecular" weights- Brepamtiozt-eoje.2eallcyle-2=allcanolse 2=alkyl=2=alkanols are prepared'b'y reacting a mono-alkyl methyl carbinol with ethylene. at temperatures of room" temperature to 300 1, preferably-100 C. to- 250 and-at prcssures of p. sr'i; grto 2500p. s.'i; g .,preferablyi-25m4l500 p. s. .i. g., ancl in the presence of1.-a pe1toxide- -activator;

Temperatures much above 900 C5 are-to be avoided because at thislevelidecompositionlofithe peroxide activator is too -rapid for-.greatest efiectiveness to be realized." 7

The pressure at which the.reaction..is.carried out depends-.upon the: moleculareweightxot; the alcohol product 'desired'. Generally the-pressure ranges:citediaboveearezsuitables Eorrexample; to produce an" average C'1'2 aloohorfrom ethylene gen peroxide, t-butyl perphthalate or peradipate, acetyl peroxide, urea .peroxide, or mixtures of two or more of the same. 30

and isopropanol pressures of about 500 to 1000 p. s. i. g. are desirable. Uniform pressure is maintained by continuous addition of the olefin to the reaction zone.

Peroxides or hydroperoxides are employed as activators for the reaction and the temperature of the reaction will depend to some extent upon the particular peroxide employed. Temperatures in the range of 50-250 C. have been found suitable. For example, one can operate in the range a total of 0.01 to 0.5 part of activator is employed per part of olefin charged to the reactor. The amount of activator employed depends on several factors among which are molecular weight of product desired and method of activator addition to the reaction. When operating a batch process it is preferred that the activator {be added in increments to the reactor since in this manner the reaction proceeds more uniformly and better reaction rates and more uniform products are obtained. Suitable peroxides are di-t-butyl peroxide, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, hydroperbenzoate, di-t-butyl Dehydration of Z-alkyZ-Z-alkanols or by catalytic dehydration. The alcohols of the above type yield Z-alkyl-l-alkenes readily by the simple application of heat, however, care should betaken to keep the dehydration temperature :below that at which isomerization of the 2-alkyl- 'l-allrenes takes place. much above about 350 C. are to be avoided. The dehydration runs smoothly at temperatures of BOO-325 0.

Contact agents such as solid phosphoric acid,

Generally temperatures 40 clay, alumina, bauxite, etc. are also suitable as dehydrating agents. In this method the alcohol is passed through a heated column of the solid maintained at a temperature of 250-350 0., preferably 2'75-325 C. When using alumina, temperatures below about 325 C, are preferred since at higher temperatures isomerization to beta olefins or type II olefins of the formula R-CH=CH-R tends to occur.

The dehydration may also be carried out by distilling the alcohol in the presence of a catalyst such as the mineral acids, e. g., H2804, HaPoi, etc. Generally about 0.01 to 0.1 wt. per cent H2SO4 based on the weight of the alcohol being heated will suffice to cause rapid and smooth dehydration of the alcohol.

The preferred method of carrying out the dehydration consists in the heating the alcohol with a small catalytic amount of H2804 as outlined above and in the presence of an entrainer for the water produced. Cyclohexane is an outstanding carrier for the water, although other entraining agents may be employed such as certain aliphatic ethers, e. g., isopropyl ether, tertiary butyl methyl ether, tertiary butyl ethyl ether, etc., and such compounds as butyraldehyde, ethyl nitrate, etc. Preferably an entrainer is chosen whose aqueous azeotrope boils below the boiling point of the olefin. Even entrainers forming a ternary azeotrope with water and the olefin may be used if desired. Aromatic hydrocarbons of the benzene series are also suitable but the lower members of the series, benzene and toluene, are not preferred because of their tendency to react with the olefin to form alkyl aromatics under the conditions employed for the dehydration.

Typical examples of alcohols produced by reacting mono-alkyl methyl carbinols with ethylene are shown in Table I. In these runs di-tertiary butyl peroxide was employed as the activator. Ethylene was reacted with isopropanol in runs 1 to 6 and run 8, while run 7 was carried out with secondary butanol.

TABLE I Run No l 3 4 5 6 7 Alcohol Isopropyl Isopropyl Isopropyl Isopropyl Isopropyl Isopro yl 2-Butanol.

s (99%) (99%). (99%). (99%) 9%) Vol. (ml.) 500 1,000 1,800 1,800 -1 1,040. DTBP (Gm.) L 59.5 .n 59.6 59.5 .5 59.5. Wt. Product 1 520 0 0 0 650. Reaction Temp. C 145"! C-.. l7 C-" -7 0. 1457 C- 145. Reaction Press. (p. s. i.) 1,000 ,000 1,000 500 .1 1,000. Alcohol Product Distribution (by distillation), Vol.

Percent Overhead:

Boiling Point 2-Alkyl-2slkanols 200 C. at 760 mm. (Cs-C9) 200-340 C at 760 mm. (Cu-C17) 340 O. at 760 mm. (010+) Run N 8 Continuous Reaction Isopropanol-ethylene.

Temperature... 0.

Pre ure 800 p. s. i.

Liquid Feed Rat 1.27 1.1111.

DTBP Gone. in Liq. Feed 5 7.95 g./l.

Contact Time in Reactor 2.75.

Percent Alcohol Product in Reactor Eiliuent Alcohol Product Rate (gins/Hr.) Alcohol Product: Average Mol Wt Distribution, Vol. Percent Overhead: Boiling Point 200 0 Boiling Point 200-340 C Boiling Point 340 C 1 DTBPdi-t-butyl peroxide. it added initially, it added at hours 1, 2, 3 and 4 after reaching reaction temperature. Run terminated after In a run where all the DTBP was added initially, using the same conditions as run 3, 480 grams of product were 5 hours reaction time. recovered.

* Product recovered by removing unreacted alcohol at a 3:1 reflux ratio in a Bil-plate Oldershaw column.

3 Solution of di-t-butyl peroxide (DTBP) in 99% isopropyl alcohol.

eamm

Alphas tertiarysolefins tare prepared: from :the alcoholaproduced trunsilito-firastfollows; I

Aafraction .ofthe.productafromruna ((Table-I) boiling,v in-ithei-ranger of 5751* to.l05;f G. atifis mm-c- Hg; (aboutl80e220i atz'760. mm.) liquid havingitl eicompositionz was zaiwater clear percent H2504 as catalyst and cyclohexane as entrainer for the water remoyed during-dehydration. The dehydrated product was washed with ilute-NaQH z 51%. and Waterv otremors-r s du arid-z e; ycloh xane remainingin th -product was removedzby distillation-1 Thezproductj w s xyecnefree and s ver-a ebromine numb r :109; Thel;. avcra ei mol ular: wei h -i was det rm n d cryoscopicallyas bein .:135.= Infrared-absorption data identified the: product; as. being; predomie nantly type III:"olefin:(St T0ne 'absorptiom-atil-lQd m-icronsindicating;type-lfi olefinsislight:absorption at 212;]. imiororis,v the absorbingregion-of type IV c oleiins; and no absorption in the regionof ;3;';and 10;9g microns, the region of; 2 type; II"; and typeeLolefins respectively): Itsisnthereforecone eluded from these, data that theafinal product; was predominantly a mixture oi the tWQsOlBfiHS and The product with the average composition of a Clo-olefin would have a molecular weight of 130 and a bromine number of about 107. These data are in Very close w agreement with experimental at Earaxnple? tertiary alcohols and able I) v oil n 1 :10::

de ractioni ronrrunriiboil nsoiai he of 99-103 C: at 7641;. was dehydrated, over alumina at 320-3250. the range of 30 38 -G: and was identified-*b-yiintras red--'analyses:as being a mixturepf ceolefins, vim 2-methyl butene-1 (ty-pe III)-and 2-methyl butene-2 (type Iv respectivelyt Intra red abserpe tionidata indioate that-thelatter type predom-i nated. Inspection-d the infra-red data indicate thatthere wastwice as much typeIV olefinastyp I-r It has been found; thatizsalkylgzealkanpls liay ing less than 7 carbpngatomstproduced by the reaction ofa mono-alkyl methyl carbinol and ethylene that is, 2-alkyl-2-alkanol's containing 5-;land 6 carbon atoms per molecule) do not yield; a predo minance; 01; type III; olefin whennsuclpalcohols are subjected ,to dehydration.- However-,5 those 2;-al l;yl-2-alkanols contain-m Tami-more ar i toms per mo ecu e dQyie d rp edo nie nance of; type 111- olefins upomdehydratiom ample l ate at a C5 lc ho producedlhr: the reaction r sopronanol witn. ethylene pro: uc s on de ydrationapredominance: .i mQZ V ol n nd ma l quantities i; that; efi T is s; contrasted. with. the experime taledataty fied: yvExamp e nt which a 2ealkyle ealkawn 1] boi ing in the C7 v ai e which? empnstrates that a 2-alkyl-2-alkanol containjng,. 7 carbon; atoms yields on dehydration to type III olefins and 25-30% type-II olefins with no type IV.- olefin observed Ex mp A fractionofthe-product of run:8:was co1lected imthetboilingcrange at r -1658- Ct at 760 mm, the major portion of the-fractio being-obtained! in theran eiorilrioammc;ameomm- The total fraction was dehydrated over alumina at 330- 345 C. and the product then distilled. Approximately 75% of thesampleboiled in the range of 8893.5 C., fractions being obtained representing 1 C. boiling ranges. All fractions gave bromine numbers in the range of 162 to 165 which correspond to the bromine nu-mbers of quite pure C7 gi gling, ri o fi ri werer dentified szemethyiw hep ehcd; (ty e; 1) and =methyle tenee i -4, and-5 (type II). Infra-red absorption data indicated that the fractions/contained 70 to 75% p i-l l-o efins-and-.1 5:1toa30 ype e at e esult d om: s ittin of; h vd. hie ondss ti he pelv Ia-andcw l fins-att hei r hi deh dra on mperatu e sin datae hqwu-im Example-2 indicate-that the: alcohols in the; range nd ehy r t dsat-= fle f yi ld;Quite: pureitype III olefinsand no; type IIolefinst Exam e (a) To overhead temperatures. of: 2002 G2: 1':-"'x 30.fi" columnx packed withe.16k x .16 :protruded stainless steel tpaokingw 10%11 reflux.-i-rati o,- atmosphereidistillation.

, (19 %Twoverlioadtemperatureeof wfl -C.z same The product boiled in column and reflux ratio, vacuum distillation at 1-3 mm. Hg.

To overhead temperature of 470 0.: Engler distillation at 0.3-0.5 mm. Hg.

The total product taken overhead represented 80% of the sample charged to the still. A number of fractions were taken at regions where plateaus were indicated. These fractions represented about 70% of the total product. Data on these fract1ons are summarized below:

Bromine No Aver. No. B. Pt. 0 Atoms Percent Total Fraction No. i tangte of Per M 019 olefins m Theor. Found 180-194 11 a. 5 102. 2 ca. 9 2311-240 1 87.5 83.2 95.2 255-270 15 75. 2 71. 0 e3. 1 300-510 17 57. 0 c2. 0 c2. 5 331-353 20 5'1. 2 54. 1 94. s 353-362 20. 5 55. s 52. 5 94. 0 352-359 22 52.0 51.8 92.0 369-591 22.5 48.7 45.8 94.2 3411-414 1 25 45.2 44.8 98.1 414-454 28 40.8 31.5 92.5 434-468 30 3s. 1 37. s 97. 9

1 Estimated from boiling point data.

In all cases infra-red data indicated that the fractions contained a majority of type III olefins, i. e. 2-methyl-1-alkenes, and as indicated from the above data the fractions contained 92-99% olefins.

Example 6 The bromine number of an equal weight mixture of C12 and C14 olefins would be 88 cg. Brz/g.

Ewample 7 1100 ml. of 99% isopropanol and 15 ml. of ditertiary butyl peroxide were charged to a 3 liter-autoclave and the system was then flushed with ethylene. The temperature of the reactor was then raised to 145 C. at which time the pressure was adjusted to 1000# and maintained at this pressure for the duration of the run by continual addition of ethylene. At hours 1, 2, 3 and 4, after reaching reaction temperature, 15 ml. portions of di-t-butyl peroxide were added to the reactor. At the end of the fifth hour the run was terminated.

After distilling unreacted alcohol from the reaction mixture, a total of 580 g. of liquid product was recovered. This product showed strong infra-red absorption in the regions of 3.0 and 8.4-8.6 microns which is indicative of tertiary alcohols. The average molecular weight of the product was determined cryoscopically as being 226 (Cm-alcohol).

The total product was dehydrated in cyclohexane solution using about 0.1% H2804 as the catalyst. A total of 441 ml. of water was recovered indicating essentially complete dehydration had. occurred. The washed and dried product was again examined by infra-red scanning and showed no appreciable absorption at 3.0 microns or 8.4-8.6 microns, but showed strong absorption bands at 6.0 and 11.25 microns. These observations indicate a high concentration of type 111 olefifins in the dehydration product. The bromine number of the dehydrated product was 71.4 cg. Brz/g. indicating an olefin concentration of about 94% (calculated as a C15 olefin). The product was composed of olefins oi the range Csto C25, the majority of which'were type III olefins of the formula where a: is 1 to 31.

Example 8 A product prepared by reacting ethanol with ethylene under the conditions described for run 3 was dehydrated over alumina at 328 C. Infrared absorption data indicated that a mixture of types I, II and III olefins were obtained, the type II olefins representing the major portion of the product.

Example 9 A product prepared by reacting methanol with ethylene under the conditions described for run 3 was dehydrated over alumina at 325 C. As in the previous example the product contained types I and II olefins, the type II olefins again representing the major portion of the product. Approximately -80% of the product was type II olefins and 20-25% type I olefins.

Although the invention has been described with respect to reactions of isopropanol and secondary butanol with ethylene, it is equally applicable to higher secondary aliphatic alcohols wherein the secondary alcohol contains a methyl group attached to the carbinol group, e. g. propyl methyl carbinol, isopropyl carbinol, butyl methyl carbinol, isobutyl methyl carbinol, etc. However, mono-alkyl methyl carbinois containing 3-6 carbon atoms per molecule are the preferred members of the series.

What is claimed is:

1. Process for producing liquid alpha-tertiary mono-olefins of the type:

where R is a straight chain alkyl radical of 4 to 30 carbon atoms and R1 is an alkyl radical of 1 to 4 carbon atoms, which comprises reacting a mono-alkyl methyl carbonol with ethylene in the presence of a peroxide activator selected from the group consisting of ditertiary butyl peroxide and tertiary butyl hydroperoxide at a temperatur in the range of C. to 250 C. for a period of 1 to 5 hours and at a pressure in the range of 250 to 1500 p. s. i. g. to produce a mixture of 2-a1kyl- 2-alkanols oi the type: 1

GOHCHs where R. is a straight chain alkyl radical of 4 to 30 carbon atoms and R1 is an alkyl radical of 1 to 4 carbon atoms, and dehydrating the mixture of 2-alkyl-2-alkanols to yield alpha tertiary mono-olefins.

2. Process for producing liquid alpha tertiary mono-olefins of the type:

where R is a straight chain alkyl radical of 4 to 24 carbon atoms and R1 is a methyl radical, which comprises reacting isopropanol with ethylene in the presence of a peroxide activator selected from the group consisting of ditertiary butyl peroxide and tertiary butyl hydroperoxide at a temperature of 100 to 200 C. for a period of 1 to 5 hours and a pressure in the range of 500 to 1500 p. s. i. g. to produce a mixture of 2-alkyl-2-alkanols of the type:

where R is a straight chain alkyl radical of 4 to 24 carbon atoms and R1 is a methyl radical, and dehydrating the mixture of 2-alkyl-2-alkanols to yield a mixture of alpha-tertiary mono-olefihs.

3. A process according to claim 1 in which the dehydration of th 2-alkyl-2-alkanol is carried out by distilling the 2-alkyl-2-alkano1 with H2804 as a catalyst in the presence of cyclohexane as an entrainer for the water.

4. A process according to claim 1 in which the monoalkyl methyl carbinol contains 3 to 6 carbon atoms per molecule.

5. A process according to claim 1 in which the mono-alkyl methyl carbinol is isopropanol.

6. A process for producing 2-alkyl-l-alkenes containing 7 to 27 carbon atoms per molecule which comprises, reacting isopropanol with ethylene in the presence of di-tertiary butyl peroxide at a temperature of 100-200 C. for a period up to about hours and at a pressure in the range of 500-1500 p. s. i. g. to produce 2-alkyl2-alkanols containing 7 to 27 carbon atoms per molecule, and dehydrating the 2-alkyl-2-alkanols to yield 2-a1kyl-1-alkenes.

7. A process according to claim 6 in which the dehydration is accomplished by distilling the 2-alkyl-1-alkanols at a temperature not above 350 C.

8. A process according to claim 6 in which the dehydration is accomplished by passing the 2-alkyl-2-alkanols over alumina at a temperature of 275-325 C.

9. A process according to claim 6 in which the 10 dehydration is accomplished by distilling the 2-alkyl-2-alkanols with a small catalytic amount of H2804 in the presence of a water entrainer.

10. A process according to claim 9 in which the water entrainer is cyclohexane.

11. A process for producing 2-alkyl-1-alkenes containing 8 to 26 carbon atoms per molecule which comprises reacting secondary butanol with ethylene in the presence of ditertiary butyl peroxide at a temperature of -250 C. for a period of about 5 hours and at a pressure of 500-1500 p. s. i. g. to produce 2-alkyl-2-alkanols containing 8 to 26 carbon atoms drating the 2-alkyl-2-alkanols to yield 2-alkyl-1- alkenes.

12. A process according to claim 11 in which the dehydration is accomplished by distilling the 2-alkyl-1-alkanols at a temperature not above 350 C.

13. A process according to claim 11 in which the dehydration is accomplished by passing the 2-alkyl-2-alkano1s over alumina at a temperature 01' 275-325 C.

14. A process according to claim 11 in which th dehydration is accomplished by distilling the 2-alkyl-2-alkanols with a small catalytic amount of H2SO4 in the presence of a Water entrainer.

15. A process according to claim 14 in which the water entrainer is cyclohexane.

FRED W. BANES. WILLIAM P. FITZ GERALD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,012,785 Deanesly et al Aug. 27, 1935 2,058,435 Fisher Oct. 27, 1936 2,076,111 Bannister Apr. 6, 1937 2,345,625 Palmer et al Apr. 4, 1944 2,402,137 Hanford et a1 June 18, 1946 2,512,649 Howard et a1. June 27, 1950 2,517,732 Stiteler et al Aug. 8, 1950 OTHER REFERENCES per molecule, and dehy-- 

1. PROCESS FOR PRODUCING LIQUID ALPHA-TETIARY MONO-OLEFINS OF THE TYPE: 